The Chemsex Monologues weaves the stories of four characters who separately narrate their individual experiences in drug-fuelled chill-outs – post-club parties – the strands of their lives loosely threading them together.

Patrick Cash’s tale of a part of post-gay club culture introduced me to a whole new world (and lexicon). G for those that don’t know (me) is, what 90s kids like me knew as GHB, and GBL, drugs that give users a euphoric high on a knife-edge; the dosage to reach that high is dangerously close to the level at which users can overdose.

The story is dark, funny and unflinching, but there is never any moralising over the characters’ occasionally ill-advised actions. There is a bleak under current to each monologue, but no one is cast in a tut-tutting light.

The characters are – crucially – engaging and all four actors bring a emotional weight to their roles, not easy when there is no one on stage to spark off.

Matthew Hodson as sexual health worker Daniel is a joy, a red wine sipping oddity among G-ed up party goers. His goodness is endearing and never patronising – his character could tip over into a camp parody with the joke firmly on him and his Freddie Mercury-loving enthusiasm, but it’s only ever sincere, warm and funny – and we’re laughing with him, not at him.

But Daniel’s story comes towards the end. First we meet our narrator (Kane Surry), on the night he meets a pretty boy – Nameless – on an all-night bender during a weekend back in London from his base in Paris. He is introduced not only to Nameless, but to G and chemsex before they drift apart 24-hours later under the halcyon lights in Vauxhall.

Nameless – played with frenetic energy that combines innocence with a toughness – by Denholm Spurr – is up next. He relives the day he met Saint Sebastian, a celebrated porn star, rollerskating down Old Compton Street wearing nothing but hot pants and angel wings. They meet again at Hustlaball before heading back to Old Mother Meph’s where events turn from euphoric to chaotic, fun to nearly fatal.

We’re back at Old Mother Meth’s again with Fag Hag Cath. A young and newly single mother who is looking forward to spending Valentine’s Day with her best friend, Steve. But the scene back at Old Mother Meth’s has a nasty edge that Steve looks likely to step over into a darker place.

The Chemsex Monologues is a sensitive portrayal of a world where heavy drugs and delicate minds collide in frank, witty, sometimes heartbreaking ways, each story brought to life by Cash’s sharp script and performances that dig deep into their characters.